Return-flue for stoves and the like.



No. 825,747. PATENTED JULY 10, 1905.

l P. W. MOLDENHAUER & DORNPELD.

RETURN PLUE FOR STOVES AND THE LIKE.

APPLICATION FILED APR IB. 1906.

, UNITED STATES FREDERICK MOLDENHAUER,

PATENT OFFICE.

or oooNoMowoo, AND LOUIS DORNFELD, OF WATERTOWN, WISCONSIN.

RE'T'UBN-FLUE. "FOR swo'vEs "AND THE LIKE.

"To all whom it may concern:

Be it known that we, FRED RICK W. Mor- 'DENHAUER, residing in OCOIIOHIOWOO, county of Waukesha, and LOUIS DORNFELD, residing in Watertown, county of Jefferson, State of Wisconsin, have invented new'a'nd useful Improvements in Return-Flues for Stoves and the Like, of which the following is a descrip- I tion,reference being had to thefaccomp'anying drawings, which are a part of this sp'ecifi- 'cation.

The object of this invention is to improve upon the construction of return-fines, so as to avoid the formation of soot-collecting pockets in the smoke-pipe, whichin former construc- 'tions have Obstructed fthe passage-way and,

interfere with the proper operation.

Another objectof this invention is to provide for deflecting the inflow of fresh air to the return fiue in such a manner that it will be impossible for it to commingle with-the smoke and ases passing up I the smoke-pipe when the val ve or gate is in an intermediate position. j

Another object of this invention is to so "construct" the valve or gate that it may project into the combustion-chamber of the stove andthere divide the smoke and gases to be returned from the steam and gases to be discharged, resulting in a more efficient operation than in formerstructures where the division was made within the smoketpipe.

Another object of this invention is "to mount the valve or gate in such a manner.

that soot deposited thereon may be returned to the combustion-chamber.

With "the above and other objects in view the invention consists in the return-flue as hereinidescribed and claimed, its associated parts and combinations thereof, and all equivalents.

Referring to the accompanying drawings, in which like characters of reference indicate -the-same :parts in the several views, Figure :1 is a sectional elevation of a fragment of a heating-stove provided with a return-flue constructed in accordance with this invention. Fi 2 is'aside elevation of the returnied from the stove, and Fig. 3 is a sectional view thereof on the plane of line 3 3 of Fig. 2.

In the drawings, 5 represents a fragment of an ordinaryheating-stove having'a .grate 6 Specification of Letters Tatent. Application filed April 18, 1906. Serial No. 312.349-

and a fire-pot 7, with a combustion-chamber 8 thereabove and an ash-pit 9 therebelow, all of usual construction. While the invention is shown in connection with'this particular form of heating-stove, it is to be understood that it is notlimited in its application "to such stove, but may be attached to or constitute a part of any suitable heating apparatus, such as a'furnace or a range or the like.

. A valve-chamber '10, rectangular in crosssection, isprovided with a curved collar 11 to fit the contour of the stove-body and takes the place of the ordinary elbow connection for the smoke1pipe 12, which is here connected with the valve-chamberby means of the StOVGPlPB" connection 13, leading from *the -top of said valve-chamber close to the stove.

The bottom of the valve-chamber is conash-pit of the'stovebeneath thei-gratefso that there is a complete return conductor or return-flue from the combustion-chamber 8 through the valve-chamber 1-0 and thereturnpipe 14 to the space beneath the jfire bed on the grate. At that meeting edge of the stove- .pipe connection 13 with the valve-chamber 10 which is farthest from the combustionchamber is ournaled a shaft 15, carrying a valve 16, with its side edges closely fitting chamber and its free end projecting within the combustion-chamber. The valve 16 is preferably of sheet metal with the free end portion bent to an arc shapein cross-section for the double purpose of closely fitting against the curved lower edge of the valvechamber when in its lowerposition and j of forming a small passage-wayat the top offthe valve-casing from the combustionchamber to the stovepipe connection when in its upl per position, and therel ay, preventing the .pos-

sibility of entirely closing'the outlet to the smoke-pipe for thelighter s aces.

On the ouside of the va ve-chaniber the -shaft1'5 has pivotally connectedtoit a crankliandle 17 by means of which the valve may be swung from one position to another and which is adapted to be lockedin its various adjustments by engaging with the teeth of an arc-shaped rack 18, secured to the valvechamber.

A cold-air e19 connects with the upper part of the va ve-chamber close to thepivotal connection of the valve "and is always in nected by means of a return pipe 14 with the against the parallel side walls of the valve-z communication with the return-pipe 146A deflector-plate is located in the valvechamber and extends downwardly from a position near the pivotal connection of the valve, so as to deflect the inflow of fresh air from the cold-air pipe away from the valve and the passage-way for the smoke-pipe through the valve-chamber. The fresh-air pipe 19 leads u wardly from near the floor and is provide with a valve or damper 21 for closing the communication therethrough when desired.

In operation the valve 16 is in its closed position, as shown in full lines in Fig. 1, while the fire is being started, and in this position the drafts are the same as the direct draft in the ordinary flue constructions, except that fresh air is taken beneath the grate through the cold-air pipe 19 instead of through the ash-pit door, as usual. With this direct draft there is no return of the gas to the grate, for the valve 16 tightly closes the return-flue and the gases pass unimpeded.

through the stovepipe passage-way of the valve-chamber to the chimney. When the fire has become fairly started, the crank-handle 17 is moved upwardly to lift the valve 16 to any desired position, which will depend upon the nature of the fuel being burned, the

usual position of the valve with hard coal being its full open position against the upper wall of the valve-chamber, as shownin dotted lines. in Fig. 1. Now the smoke and gases coming from the combustion-chamber will for the greater part be drawn by suction downwardly through the return-pipe 1 1, where they will commingle with and heat the fresh air drawn in by induction through the cold-air pipe 19 and become thoroughly intermixed therewith during the passage down the return-flue, so that as the mixture enters the chamber beneath the grate it is in a perfectly combustible state, and on passing through the grate and into contact with the live coals it will burn freely and contribute to the heating effect. Inasmuch as the stovepipe passage-way through the valve-chamber cannot be completely closed bymeans of the valve 19, even when in the full open osition, the steam and lighter non-combusti le. gases which naturally travel along the top of said passage-way are permitted to separate from 'the smoke and heavier combustible gases by passin through the small passage-way provided by the curvature of the valve or through the space above the valve and escape by way of the chimney. The valve 16, therefore, in addition to its valvefunctions of opening and closing the various passages, serves as a gas-separator operating within the combustion-chamber to select the combustible gases from the non-combustible gases and guide them to the return-flue, while allowing the non-combustible gases to escape to the chimney. In burning wood or soft coal which contain an abundance of moisture the valve 16 is preferably locked in an intermediate may pass out.

The valve 16 serves the double purpose of controlling the degree of opening through the smoke-pipe passage of the valve-chamber and also controlling the communication between the smoke-pipe passage-way and the returnflue, so that a single operation of the valve is all that is necessary to chan e the drafts from a direct draft to a return raft.

The valve 21 in the cold-air pipe is only used in event of the fire becoming too hot, when it may be closed more or less to control the supply of fresh air, and thereby the degree of combustibility of the gases introduced beneath the grate by the return-flue. Obviously the cold-air pipe 19 extends down to near the floor, so as to take the coldest air in the room, and therebyfacilitate the heating of the room.

There is no liability of the gases of combustion passing down the cold-air pipe and out into the atmosphere, because of their being lighter than the cold air in said pipe, and therefore unable to displace it, and for the further reason that the draft of the fire is drawing these gases down the return-pipe instead, and the deflector-plate 20, standing between the two inlet-passages to the return-pipe, keeps the gases and the air separate until its lower end is reached, which is some distance below the mouth of the fresh-air pi e.

Under no circumstances can col air from the cold-air pipe be drawn by the draft in the chimney past the valve 16, because of the tight fit of the valve in the valve-chamber in all of its positions and because of the further fact that the opening of this cold-air pipe into the return-flue is beneath the valve and the passage ofthe hot gases through the space opened by the valve effectively prevents any passage of air in the opposite direction.

Soot which may be dropped from the smoke-pipe onto the valve is not retained thereby to form an obstruction to the smokepipe passage-way, but owing to the inclined position of the valve when lowered any deposit thereon may slide down into the combustion-chamber.

The separation of the combustible from the non-combustible gases within the combus-' tion-chamber is found in practice to be far more efiicientthan such separation when made in the smoke-pipe after leaving the combustion-chamber.

. The means for moving the valve from one position to another and looking it in its adjusted positions is simple in its construction and avoids the necessity for interior connections through openings in the smoke-pipe.

What we claim as our invention is 1. In a return-flue for stoves and the like,

a connection having a smoke-pipe passage, a return-pipe leading from the smoke-pipe passage to beneath the grate, a valve for control ling communication between the smoke-pipe passage and the return pipe and projecting into the combustion-chamber, and a cold-air pipe communicating with the return-pipe between the valve and the discharge end of the return-pipe.

2. In a return-flue for stoves and the like, a valve chamber having a smoke-pipe passa e-way, a returnpipe leading from the vaIve-chamber to beneath the grate, a valve pivotally connected in the valve-chamber so as to nearly close the smoke-pipe passageway in one position and to close the returnpipe in another position, said valve having "its free end projecting into the combustionchamber, and a cold-air pipe communicating with the return-pipe between the valve and the discharge end of the return-pipe.

3 In a return-flue for stoves and the like, a valve-chamber communicating with the combustion-chamber and having a stovepipe connection, a valve pivotally connected "in the valve-chamber beyond the stovepipe connection and extendin into the combus tion-chamber, said valve eing curved to fit the wall of the combustion-chamber and to provide a passage between the valve and the top of the valve-chamber for the escape of gases to the smoke-pipe when the valve is in the upper position, a cold-air pipe communieatin with the valve-chalmber, and a return pipe eading from the valve-chamber to beneath the grate.

4. In a return-fiue for stoves and the like, a valve-chamber having connection with the combustion-chamber, a valve pivotally connected at the upper wall of the valve-chamber, a smoke-pipe connection for the valvechamber located directly above the valve and adapted to be nearly closed by the valve when the valve is in its upper position, a coldair pipe communicating with the valve chamber, and a return-pipe leading from the valve-chamber to beneath the grate.

5. In a return-flue for stoves and the like, a valve chamber having connection with the combustion-chamber, a valve pivotally connected at the upper wall of the valvechamber, a smoke-pipe connection for the valve-chamber located directly above the valve and adapted to be nearly closed by the valve when the valve is in its upper position, a crank-handle connected with the valve on the outside of the valve-chamber, a rack to be engaged by the crank-handle for locking the valve in its adjusted positions, a cold-air pipe connecting with the valve-chamber beneath the valve, and a return-pipe leading from the valve-chamber to beneath the grate.

'6. In a return-flue for stoves and the like, a valve-chamber having connection with the combustion-chamber, a valve pivotally connected at the upper wall of the valve-chamher, a stovepipe connection leading from the valve-chamber above the valve, a cold-air pipe connecting with the valve-chamber beneath the valve, and .a deflecting-plate leading downwardly from near the valve to defleet the inlet of cold air downwardly into the return-pipe.

In testimony whereof we afiix our signatures in presence of two witnesses. Y

FREDERICK W. MOLDENHAUER. LOUIS DORNFELD.

Witnesses to Frederick W. Moldenhauers 

